1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method.
2. Description of the Related Art
In fabrication of a semiconductor device, lithography processing is performed to form a resist pattern on a semiconductor wafer that is a substrate or an LCD substrate. In the lithography process, coating processing for applying a resist on a front face of the substrate, developing processing for performing developing processing for the exposed substrate, heat processing which is performed before and after the exposure processing and after the developing processing, cooling processing for cooling the substrate to a predetermined temperature after the heat processing, and the like are performed.
In the aforesaid heat processing, there are prebaking processing for performing vaporization of a remaining solvent in the resist, post-exposure baking processing for reducing deformation of a resist pattern before the developing, post-prebaking processing for vaporizing remaining wafer after the developing, and the like.
Such heat processing for the substrate is performed by heating a hot plate to a predetermined temperature by means of a heater that is a heating element and mounting the substrate on the hot plate in a heat processing apparatus. However, there usually arises a temperature difference between the temperature of the hot plate and the temperature of the front face of the heated substrate because heat energy is lost when being transmitted. Hence, the difference is set as an offset value in advance and the hot plate temperature is set at a temperature higher than a target processing temperature for the substrate by the offset value so as to heat the substrate at a predetermined temperature.
However, in the case where heat processing is performed at a plurality of target processing temperatures in one heat processing apparatus, since the offset value is different with respect to the target processing temperature, it is necessary to reset the offset value for every change, thereby bringing about deterioration in throughput. If the offset value is fixed at one value, the substrate can not be heated at an optimal temperature, thereby causing deterioration in yield.
The present invention is made under the above circumstances and an object thereof is to provide a substrate processing apparatus and a substrate processing method in which when a substrate is temperature-controlled at a plurality of target processing temperatures in one substrate processing apparatus, the temperature of a plate on which the substrate is mounted is automatically changed to an appropriate temperature based on an offset value corresponding to the target processing temperature.
To attain the above object, in a main first aspect of the present invention, provided is a substrate processing apparatus comprising: a plate on which a substrate is placed and including temperature control means for setting the substrate at a target processing temperature; storage means for storing a plurality of the target processing temperatures and a temperature difference between the target processing temperature and an actual temperature of the plate when the plate is set at the target processing temperature for each of the plurality of target processing temperatures; and control means for controlling the temperature control means to change the temperature of the plate based on the temperature difference stored for each of the plurality of target processing temperatures.
According to the above configuration of the present invention, the temperature of the plate can be automatically changed with considerations of a temperature difference between each of the target processing temperatures and the actual temperature of the plate with changes in target processing temperature for the substrate. Therefore, even if the target processing temperature for the substrate is changed, the substrate is processed at an appropriate temperature, thereby improving yields. Further, it is unnecessary to reset the temperature of the plate for every change, resulting in improved throughput.
In a second aspect of the present invention, provided is a substrate processing apparatus comprising: a plate on which a substrate is placed and including temperature control means for each of partitioned areas for setting the substrate at a target processing temperature; storage means for storing a plurality of the target processing temperatures and a temperature difference between the target processing temperature and an actual temperature of the plate when the plate is set at the target processing temperature for each of the plurality of target processing temperatures for each of the areas; and control means for controlling each of the temperature control means to change the temperature of the plate in each of the areas based on the temperature difference stored for each of the plurality of target processing temperatures.
According to the above configuration of the present invention, even if the target processing temperature for the substrate is changed, the plate temperature is individually changed by the heating element individually provided in each area, whereby the substrate is temperature-controlled at an appropriate temperature. Further, non-uniformity in temperature control within the same substrate can be corrected, whereby the substrate is uniformly temperature-controlled, resulting in improved yields.
In a third aspect of the present invention, provided is a substrate processing method for temperature-controlling a plate to set a substrate on the plate at a target processing temperature comprising the steps of: storing a plurality of the target processing temperatures; storing a temperature difference between the target processing temperature and an actual temperature of the plate when the plate is heated to the target processing temperature for each of the plurality of target processing temperatures; obtaining a predetermined temperature to which the plate needs to be temperature-controlled based on the target processing temperature and the temperature difference; and temperature-controlling the plate to the predetermined temperature.
According to the above configuration of the present invention, it is possible to store a plurality target processing temperatures for the substrate and temperature differences between the target processing temperatures and actual plate temperatures corresponding to the target processing temperatures and obtain the plate temperature from those values to change the temperature of the plate. Accordingly, even if the target processing temperature for the substrate is changed, the substrate is processed at an appropriate temperature, thereby improving yields. Further, since the plate temperature is automatically changed, it is unnecessary to reset the temperature of the plate for every change, resulting in improved throughput.
In a fourth aspect of the present invention, provided is a substrate processing method for temperature-controlling a plate to temperature-control a substrate on the plate to a target processing temperature comprising the steps of: storing a plurality of the target processing temperatures; storing a temperature difference between the target processing temperature and an actual temperature of the plate in each of partitioned areas of the plate when the plate is temperature-controlled to the target processing temperature for each of the plurality of target processing temperatures; obtaining a predetermined temperature to which the plate needs to be heated for each of the areas based on the target processing temperature and the temperature difference; and temperature-controlling the plate to the predetermined temperature.
According to the above configuration of the present invention, even if the target processing temperature for the substrate is changed, the plate temperature is individually changed in each area, whereby the substrate is heated at an appropriate temperature. Further, non-uniformity, in heating temperature within the substrate plane is corrected, whereby the substrate is uniformly processed, resulting in improved yields.
In a fifth aspect of the present invention, provided is a substrate processing method comprising the steps of: mounting a first substrate on a hot plate including a heating element and set at a predetermined temperature and heating the first substrate; removing the first substrate from a top of the hot plate; heating the hot plate at a temperature higher than the predetermined temperature and thereafter heating the hot plate at the predetermined temperature; and mounting a second substrate on the hot plate and heating the second substrate.
According to the above configuration of the present invention, even if the temperature of the hot plate decreases to be lower than the predetermined temperature due to the processing for the first substrate, the hot plate is heated at a temperature higher than the predetermined temperature before the second substrate which is subsequently processed is carried in, whereby the hot plate can be quickly returned to a desired predetermined temperature, resulting in improved throughput.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.